Type 2 Diabetes Mellitus (DM) is a heterogeneous medical condition characterized by high levels of blood glucose or hyperglycemia. Hyperglycemia results from either peripheral tissue resistance to insulin or inadequate insulin levels and frequently both. Although the causes of type 2 DM is poorly understood the majority of patients have inadequate insulin secretion from their beta cells. To understand how DM develops and to ultimately produce new therapies for DM we are studying the regulation of insulin secretion from pancreatic beta cells. One of the critical steps in the regulation of insulin secretion is the interaction of certain hormones and their intracellular signals with products of glucose metabolism. Binding of many of these hormones to beta cell receptors leads to the activation of the cyclic AMP dependent kinase (PKA). Activation of PKA augments glucose mediated insulin secretion. We have recently shown that to increase insulin secretion PKA must be activated at specific subcellular sites. PKA is targeted to these specific sites through the interaction of the regulatory subunit of the kinase with specific targeting proteins called AKAPs (A-Kinase Anchoring Proteins). In addition to targeting PKA several AKAPs have been identified that target other signaling enzymes. We are currently isolating AKAPs found in pancreatic beta cells and determining their role in modulating insulin secretion. This project is centered on the characterization of a recently identified AKAP, AKAP155 This AKAP was purified from rat pancreas and a transformed rat beta cell line (RINm5F) by calmodulin affinity chromatography. AKAP79, is a bifunctional AKAP targeting PKA, PKC and the type 2B phosphatase, CaN. AKAP79 is also co-purified from brain tissue by calmodulin affinity chromatography. We have previously shown that PKA and CaN are associated in pancreatic beta cells and therefore hypothesis that AKAP155 may be a bifunctional AKAP targeting both PKA and CaN. We plan to identify the full-length sequence of AKAP155 and determine the specific regions involved in binding PKA. To understand how AKAP155 may function in beta cells we will identify its subcellular targeting domain. Once these regions are identified we will develop specific inhibitors to disrupt the targeting of the complex or the individual enzymes and determine the effect on insulin secretion.